# std::vector<T,Allocator>::rbegin, std::vector<T,Allocator>::crbegin

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< cpp‎ | container‎ | vector

reverse_iterator rbegin(); | (1) | (noexcept since C++11) (constexpr since C++20)
const_reverse_iterator rbegin() const; | (2) | (noexcept since C++11) (constexpr since C++20)
const_reverse_iterator crbegin() const noexcept; | (3) | (since C++11) (constexpr since C++20)

Returns a reverse iterator to the first element of the reversed `vector`. It corresponds to the last element of the non-reversed `vector`. If the `vector` is empty, the returned iterator is equal to rend().

### Parameters

(none)

### Return value

Reverse iterator to the first element.

### Complexity

Constant.

### Notes

The underlying iterator of the returned reverse iterator is the end iterator. Hence the returned iterator is invalidated if and when the end iterator is invalidated.

libc++ backports `crbegin()` to C++98 mode.

### Example

Run this code

    #include <algorithm>
    #include <iostream>
    #include <numeric>
    #include <string>
    #include <vector>

    int main()
    {
        std::vector<int> nums{1, 2, 4, 8, 16};
        std::vector<std::string> fruits{"orange", "apple", "raspberry"};
        std::vector<char> empty;

        // Print vector.
        std::for_each(nums.rbegin(), nums.rend(), [](const int n) { std::cout << n << ' '; });
        std::cout << '\n';

        // Sums all integers in the vector nums (if any), printing only the result.
        std::cout << "Sum of nums: "
                  << std::accumulate(nums.rbegin(), nums.rend(), 0) << '\n';

        // Prints the first fruit in the vector fruits, checking if there is any.
        if (!fruits.empty())
            std::cout << "First fruit: " << *fruits.rbegin() << '\n';

        if (empty.rbegin() == empty.rend())
            std::cout << "vector 'empty' is indeed empty.\n";
    }

Output:

    16 8 4 2 1
    Sum of nums: 31
    First fruit: raspberry
    vector 'empty' is indeed empty.

### See also

rendcrend (C++11) | returns a reverse iterator to the end (public member function)
rbegincrbegin (C++14) | returns a reverse iterator to the beginning of a container or array (function template)

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